Confusion as to what the sentence means

Can someone explain to me the meaning of this sentence?

I have enough trouble overcoming my own limitations without fretting over the fact that God has not seen fit to distribute evenly the gift of intelligence.

Does this sentence mean: I have trouble overcoming my limitations even when I don't consider the fact that God doesn't distribute the gift of intelligence evenly.

This sentence is taken from the book How to Win Friends and Influence People by Dale Carnegie.

I have enough trouble overcoming my own limitations.

That's enough for me. So I make no effort to ask why God didn't distribute intelligence evenly among men.

How to Win Friends etc is a classic that sold millions of copies. Your basic analysis is correct. But Dale Carnegie is making some other points:

(1) if you are smarter than other people that is no credit to you;

(2) people do like it when you tell them they are stupid

It is a variant on the mote and the beam (Mt 7 v1-5.